[ISSUE] `databricks_vector_search_index.delta_sync_index_spec.columns_to_sync` missing

[mfogel]

The attribute databricks_vector_search_index.delta_sync_index_spec.columns_to_sync is documented but not being published in the schema spec.

To reproduce, run

% terraform providers schema -json | jq '.provider_schemas["registry.terraform.io/databricks/databricks"].resource_schemas["databricks_vector_search_index"].block.block_types.delta_sync_index_spec'
{
  "nesting_mode": "list",
  "block": {
    "attributes": {
      "embedding_writeback_table": {
        "type": "string",
        "description_kind": "plain",
        "optional": true
      },
      "pipeline_id": {
        "type": "string",
        "description_kind": "plain",
        "computed": true
      },
      "pipeline_type": {
        "type": "string",
        "description_kind": "plain",
        "optional": true
      },
      "source_table": {
        "type": "string",
        "description_kind": "plain",
        "optional": true
      }
    },
    "block_types": {
      "embedding_source_columns": {
        "nesting_mode": "list",
        "block": {
          "attributes": {
            "embedding_model_endpoint_name": {
              "type": "string",
              "description_kind": "plain",
              "optional": true
            },
            "name": {
              "type": "string",
              "description_kind": "plain",
              "optional": true
            }
          },
          "description_kind": "plain"
        }
      },
      "embedding_vector_columns": {
        "nesting_mode": "list",
        "block": {
          "attributes": {
            "embedding_dimension": {
              "type": "number",
              "description_kind": "plain",
              "optional": true
            },
            "name": {
              "type": "string",
              "description_kind": "plain",
              "optional": true
            }
          },
          "description_kind": "plain"
        }
      }
    },
    "description_kind": "plain"
  },
  "max_items": 1
}

And observe there is no mention of columns_to_sync

This shows up as an error

[Terraform] [E] Unexpected attribute: An attribute named "columns_to_sync" is not expected here

In a block like

resource "databricks_vector_search_index" "this" {
  name          = "${var.index_catalog}.${var.index_schema}.${var.index_name}"
  endpoint_name = var.vector_search_endpoint_name
  primary_key   = var.primary_key
  index_type    = "DELTA_SYNC"

  delta_sync_index_spec {
    source_table    = var.source_table
    pipeline_type   = var.pipeline_type
    columns_to_sync = var.columns_to_sync
    embedding_source_columns {
      name                          = var.embedding_source_column_name
      embedding_model_endpoint_name = var.embedding_model_endpoint_name
    }
    embedding_writeback_table = "${var.index_catalog}.${var.index_schema}.${var.index_name}_writeback_table"
  }
}

This is on provider 1.84.0, but there appear to have been no changes between 1.84.0 and 1.99 (the current release) in the source code.

Note searching this repo for ColumnsToSync or columns_to_sync yields no tests.